This grant involves research on the genetic epidemiology and interacting environmental factors in the natural history of cancer. The specific aims of the program are: (1) to search for possible associations between specific genetic markers (single or multiple) and susceptibility to cancer and other chronic diseases. If associations can be found, they will be further investigated for their value in detection of high risk individuals as well as their potential etiologic role; (2) to investigate the relative role of genetic and environmental contributions to cancer incidence by the use of genetic-distance and genetic-admixture estimates in racially hybrid populations; (3) to study the biology (chemistry, virology, and immunology) of aspirated human breast fluid and its potential value for the determination of susceptibility to breast cancer; (4) to investigate potential personality and psychological types which might predispose to cancer.